Hardware Design Of Weak Signal Acquisition Module Based On Adaptive Filtering

Data acquisition technology is widely used in electronic communication,sonar detection,opto-magnetic analysis and other fields.In recent years,with the continuous development of the above fields,the accuracy requirements of data acquisition technology are getting higher and higher.The detection of weak signals such as weak current,weak magnetic,low light and micro sound has become an important development direction of data acquisition technology.This thesis focuses on the microvolt(?V)level weak voltage signal,and achieves high-precision acquisition of wide-band(100kHz)weak signals(DC precision 0.2? FSR,AC precision 2? FSR)as the main target of the project.In order to achieve this goal,this paper combines a narrowband filter with a tunable bandpass filter to design an adjustable bandpass filter based on the LRC resonant circuit,and uses an adaptive filtering algorithm as the control algorithm for the tunable filter.A weak signal acquisition scheme based on adaptive filtering is proposed.Based on this scheme,the main work carried out in this paper is as follows:1.According to the design requirements,the system indicators are determined,the overall design scheme and module division are given,and the filter circuit design combining classical filtering and adaptive filtering is clarified.2.using variable gain amplifier(VGA),Sigma-Delta analog-to-digital converter(ADC),programmable gate array(FPGA),static random access memory(SRAM)and other devices for circuit design,clear device selection,and combined with the device characteristics,wrote the Verilog code;3.In order to curb broadband noise and improve the frequency selection characteristics of the adaptive filter module,a low-band adjustable band-pass filter structure is designed based on the LRC resonant circuit.The structure is realized by a new adjustable capacitor,which solves the varactor control channel and The frequency offset caused by signal channel sharing reduces the signal distortion rate;4.Due to the limited adjustment range of a single adjustable capacitor,in order to avoid large-scale circuit parallelization and reduce the complexity of the adaptive filter circuit,the circuit design is implemented by using the band segmentation method and the multiplexing idea,thereby improving the device utilization rate and reducing the device utilization.The hardware size reduces the implementation cost.On the basis of the above design work,combined with various technical indicators,the relevant parameters were analyzed and tested,and the feasibility of the design of the subject was verified.The test results also proved that the design can achieve high precision of the ?V level signal under the bandwidth of 100 kHz.collection.